This application relates to and incorporates by reference Japanese patent application number 2001-281930, which was filed on Sep. 17, 2001.
The present invention relates to a centrifugal ventilator fan (see JIS B 0132 No.1004) which has blades radially spaced about the axis of rotation and which operates such that air enters axially through an inlet and is discharged radially.
In a centrifugal ventilator fan disclosed in Japanese unexamined patent publication No. Hei 6-307390, the blades are smoothly twisted with respect to a plane passing through the center of the hub to improve performance. However, it is not always possible to provide improved fan performance and reduced noise levels merely by twisting the blades.
The present invention was developed in view of the aforementioned points. It is therefore an object of the invention to positively provide improved fan performance and reduced noise levels.
To achieve the aforementioned object, according to a first aspect of the present invention there is provided a centrifugal ventilator fan which has multiple blades spaced about an axis of rotation and which operates with air entering axially through an inlet at an end thereof and being discharged radially outwardly. The centrifugal ventilator fan is designed such that a first fan outlet angle of the blades at one end in a direction of the axis of rotation is less than a second fan outlet angle of the blades at the other end in the direction of the axis of rotation. Additionally, the first fan outlet angle is equal to zero degrees or greater and five degrees or less, while the second fan outlet angle is equal to thirty degrees or greater and forty-five degrees or less.
As will be seen clearly from FIGS. 5 and 6 described later, this makes it possible to provide improved fan performance and reduced noise levels.
According to a second aspect of the present invention a centrifugal ventilator fan has multiple blades spaced about an axis of rotation and which operates with air entering axially through an inlet at an end thereof and being discharged radially outwardly. The centrifugal ventilator fan is designed such that a first fan inlet angle of the blades at one end in a direction of the axis of rotation is larger than a second fan inlet angle of the blades at the other end in the direction of the axis of rotation. Additionally, the first fan inlet angle is equal to sixty-five degrees or greater and ninety degrees or less, while the second fan inlet angle is equal to fifty-five degrees or greater and seventy-five degrees or less.
As will be seen clearly from FIGS. 7 and 8 described later, this makes it possible to provide improved fan performance and reduced noise levels.
According to a third aspect of the present invention, a centrifugal ventilator fan has multiple blades spaced about an axis of rotation and which operates with air entering axially through an inlet at an end thereof and being discharged radially outwardly. The centrifugal ventilator fan is designed such that a first fan outlet angle of the blades at one end in a direction of the axis of rotation is less than a second fan outlet angle of the blades at the other end in the direction of the axis of rotation. Additionally, the first fan outlet angle is equal to zero degrees or greater and 5 degrees or less, while the second fan outlet angle is equal to 30 degrees or greater and forty-five degrees or less. The centrifugal ventilator fan is further designed such that a first fan inlet angle of the blades at the one end in the direction of the axis of rotation is larger than a second fan inlet angle of the blades at the other end in the direction of the axis of rotation. Additionally, the first fan inlet angle is equal to sixty-five degrees or greater and ninety degrees or less, while the second fan inlet angle is equal to fifty-five degrees or greater and seventy-five degrees or less.
As will be seen clearly from FIGS. 5 to 8 described later, this makes it possible to provide improved fan performance and reduced noise levels.
According to a fourth aspect of the invention, a vane surface of the blade is generally parallel to the axis of rotation.
This allows a fan mold die to easily release the fan in the direction parallel to the axis of rotation, thereby making it possible to improve the productivity of the centrifugal ventilator fan.
According to a fifth aspect of the invention, a ratio of a fan outer diameter at the other end of the axis of rotation to a fan outer diameter at the one end of the axis of rotation is equal to 0.9 or greater and 1.0 or less.
As will be seen clearly from FIG. 9 described later, this makes it possible to provide improved fan performance and reduced noise levels.
According to a sixth aspect of the invention, a ratio of a fan inner diameter at the other end of the axis of rotation to a fan inner diameter at the one end of the axis of rotation is equal to 0.9 or greater and 1.0 or less.
As will be seen clearly from FIG. 9, which is described later, this makes it possible to provide improved fan performance and reduced noise levels.
Incidentally, the parenthesized numerals accompanying the foregoing individual means show an example of correspondence with concrete means seen in the embodiments to be described later.